Hydraulic, rotary servo-actuator

ABSTRACT

A hydraulic, rotary servo-actuator of the type having a casing, a first control valve, an input shaft provided therewithin with hydraulic fluid supply and discharge passageways, and a hydraulically actuated member further has other hydraulic fluid supply and discharge passageways formed within its casing and respectively communicating with a fluid supply source and a fluid reservoir both outside the servo-actuator and a second control valve formed within the casing and operating to communicate and shut off selectively these other passageways respectively with and from the passageways formed within the input shaft thereby to prevent excessive actuated movement of the hydraulically actuated member.

United States Patent 1191 Saida et 'al.

1 1 Jan.7, 1975 HYDRAULIC, ROTARY SERVO-ACTUATOR [75] Inventors: YouichiSaida, Kawasaki; Hajime Ito, Yokohama; Kojiro Imanaga, Tokyo; Tomoji.lyumonji, Yokohama, all of Japan [73] Assignee: Mitsubishi KinzokuKogyo Kabushiki Kaisha, Tokyo-to, Japan [22] Filed: Oct. 18, 1973 211Appl.No.:407,629

[30] Foreign Application Priority Data Oct. 21, 1972 Japan 47-104862[52] us. c1 91/375, 91/376 A, 91/445 1511 1111.01. ..F15b 9/10 58 Fieldof Search 91/375, 376, 376 A. 445, 91/410 [56] References Cited UNITEDSTATES PATENTS 1,876,104 9/1932 Tucker 91/375 2,260,979 10/1941 Morin eta1. 91/375 2,372,710

4/1945 Chisholm, Jr 91/375 2,613,649 10/1952 Diehels. 91/375 3,732,0275/1973 Lupkc 91/410 FOREIGN PATENTS OR APPLICATIONS 1,928,751 12/1970 IGermany 91/445 Primary E.\'aminerPaul E. Maslousky Attorney, Agent, orFirm-Wenderoth, Lind & Ponack [57] ABSTRACT A hydraulic,rotaryservo-actuator of the type having a casing, a first control valve,an input shaft provided therewithin with hydraulic fluid supply anddischarge passageways, and a hydraulically actuated member further hasother hydraulic fluid supply and discharge passageways formed within itscasing and respectively communicating with a fluid supply source and afluid reservoir both outside the servo-actuator and a second controlvalve formed within the casing and operating to communicate and shut offselectively these other passageways respectively with and from thepassageways formed within the input shaft thereby to prevent excessiveactuated movement of the hydraulically actuated member.-

2 Claims, 9 Drawing Figures Patented Jan. 7, 1975 2 Sheets-Sheet 1Ilium! Patented Jan. 7, 1975 7 3,858,484

2 Sheets-Sheet 2 HYDRAULIC, ROTARY SERVO-ACTUATOR BACKGROUND OF THEINVENTION This invention relates to hydraulic-type, rotaryactionservo-actuators and more particularly to a servoactuator of this typeprovided with an input shaft and an output shaft coaxially disposedrelative to the input shaft and rotatably fitted on the inner partthereof and having a servo-valve at the fitted surfaces of the input andoutput shafts.

We have previously developed a hydraulic, rotary servo-actuatorcomprising a cylindrical enclosure having a plurality of dividedhydraulic fluid acting chambers, an output shaft rotatably supportedwithin the cylindrical enclosure, and an input shaft rotatably fitted ina central bore formed along the rotational axis of the output shaft (asdisclosed in the specification of U.S. Pat. application Ser. No.265,178, filed June 22, 1972, now abandoned and entitled ROTARY SERVO-MECHANISM).

A servo-actuator of this type is provided with a servovalve which,structurally, is built-in at the mutually fitted surfaces of the inputshaft and the output shaft and is adapted to return automatically to theneutral position when the output shaft rotates in response to a rotationof the input shaft. For this reason, there is no risk of the outputshaft rotating excessively beyond a predetermined maximum rotationalangle under normal operational conditions.

However, there is the possibility of the output shaft being caused byimpact force due to the hydraulic fluid entering the fluid actingchambers provided within the cylindrical enclosure to rotate beyond thispredetermined maximum angle thereby to cause pressureactuated membersfixed to the outer periphery of the output shaft to collide withpartition walls within the cylindrical enclosure and thereby to giverise to unforeseen damage to the rotating mechanism.

SUMMARY OF THE INVENTION It is an object of this invention to solve theabove described problemin a hydraulic, rotary servo-actuator.

More specifically, an object of the invention is to provide a hydraulic,rotary servo-actuator of the type referred to above in which, withoutexternally installing a special rotation control mechanism, excessiverotation of the output shaft is prevented by safety means comprising acontrol valve provided in built-in state at the fitted surfaces of theinput shaft and the cylindrical enclosure and operating when the outputshaft in rotation reaches an angular posit-ion just short of the abovementioned limiting maximum angle to shut off either one or both of thehydraulic fluid supply to a fluid supply path and the fluid dischargefrom a fluid discharge.

According to this invention, briefly summarized, there is provided ahydraulic, rotary servo-actuator comprising: a closed cylindricalenclosure having therewithin a plurality of hydraulic action chambers;an input shaft rotatably supported along the central axis of thecylindrical enclosure by a wall part thereof and having a part extendingin the interior of the enclosure; an actuated member having a partpassing through a wall of the enclosure and having a central axial bore,into which the input shaft is rotatably fitted, and further having arotor part provided with hydraulically actuated parts movably disposedwithin the hydraulic action chambers; and a first control valve providedin the central axial bore and operating to communicate the hydraulicaction chambers selectively with hydraulic fluid supply and dischargepassageways formed within the input shaft, the servo-actuator beingcharacterized in that-other hydraulic fluid supply and dischargepassageways respectively communicating with a hydraulic fluid supplysource and a hydraulic fluid reservoir both outside of theservo-actuator are formed within a wall of the enclosure, and in that asecond control valve for operating interrelatedly with the first controlvalve to selectively communicate and shut off these other hydraulicfluid supply and discharge passageways respectively with and from theaforesaid passageways formed within the input shaft thereby to preventexcessive actuated movement of the hydraulically actuated parts isprovided in a wall of the enclosure.

The nature and further features of the invention will be apparent fromthe following detailed description with respect to a preferredembodiment of the invention when read in conjunction with theaccompanying drawings, in which like parts are designated by likereference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side view, for the most part in longitudinal section,showing the essential parts of one example of the hydraulic, rotaryservo-actuator according to the invention;

FIG. 2 is a cross section taken along the plane indicated by line II IIin FIG. 1 as viewed in the arrow direction;

FIG. 3a is a diagrammatic end view showing the rotor of theservo-actuator in neutral position;

FIG. 3b is a diagrammatic end view indicating a second control valve inneutral position;

FIG. 4a is a diagrammatic end view showing the rotor in a clockwiserotated position;

FIG. 4b is a diagrammatic end view indicating the state of the secondcontrol valve corresponding to the state of rotor indicated in FIG. 4a;

FIG. Sais a diagrammatic end view showing the rotor in acounterclockwi'sely rotated position;

FIG. 5b is a diagrammatic end view indicating the state of the secondcontrol valve corresponding to the state of the rotor indicated in FIG.5a; and

FIG. 6 is a diagrammatic projection of a hydraulic fluid groove asviewed in the direction of the arrow A in FIG. 4b.

DETAILED DESCRIPTION Referring first to FIG. 1, there is illustrated anexample-of a hydraulic, rotary servo-actuator 10 according to thisinvention the principal structural parts of which are a cylindricalenclosure 1 having two ends respectively closed by end walls 4 and S ofdisc shape, an output shaft 2 formed integrally and coaxially with arotor part 7 accommodated rotatably within the enclosure 1, the ends ofthe output shaft 2 extending out through central journal holes 4A and 5Bin the end walls 4 and 5, respectively, and an input shaft 3 rotatablyand coaxially fitted within an axial bore formed in the output shaftfrom its end extending out through the central hole 58 to the middlepart of the rotor 7.

As indicated in FIG. 3a, the cylindrical enclosure 1 is provided in itsinterior with two longitudinal partition walls 6A and 6B extendingradially inward to the rotor part 7 and disposed in substantiallydiametrically opposite positions. The outer surface of the rotor part 7is engaged in a liquidtight yet slidable manner with the innermost edgesof the partition walls 6A and 6B. The rotor part 7 is provided withpressure-actuated members 7A and 7B of vane-like shape secured unitarilyat their base parts to the rotor part 7 on substantially diametricallyopposite sides thereof and extending radially outward therefrom to theinner cylindrical surface of the cylindrical enclosure 1, where theoutermost tips of the vanes 7A and 7B are engaged in a liquid-tight yetslidable manner with the inner surface of the enclosure Thus, fourhydraulic action chambers 30, 31, 32, and 33 are formed between theinner surface of-the cylindrical enclosure 1 and the outer cylindricalsurface of the rotor part 7 by these surfaces, the partition walls 6Aand 6B, and the vanes 7A and 7B.

As shown in FIG. 1, a control valve or a servo-valve 8 is provided atthe fitting surfaces of the output shaft 2 and the input shaft 3slidablyfitting thereinto. This control valve 8 is formed by hydraulicfluid recesses or grooves 9A and 9Bformed in the inner wall surface ofthe aforementioned central bore 12 of the output shaft 2 and hydraulicfluid recesses or grooves 11A and 118 formed in the outer surface of theinput shaft 3.'While not shown in the drawings, the fluid grooves 9A and9B are communicatively connected via suitable passageways to theaforedescribed hydraulic action chambers and 32 and hydraulic actionchambers 31 and 33, respectively.

The input shaft3 is provided therewithin with longitudinal hydraulicfluid passageways 13 and 14. The passageway 13 for fluid supply opens atone end thereof intothe above mentioned fluid groove 118 formed on theouter surface of theinput shaft 3 and is communicatively connected atits other end by way of a 'mechanism to be described hereinafter to ahydraulic fluid supply source (not shown) outside of the actuator. The

hydraulic fluid supply passageway 13 of the input shaft I coincides withthe fluid groove 9A communicating with the aforementioned hydraulicaction chambers 30 and 32, while the fluid groove 1 1A communicatingwith the fluid discharge passageway 14 of the input shaft registers withthe fluid groove 98 communicating with the hydraulic action chambers 31and 33, hydraulic fluid is supplied into the hydraulic action chambers30 and 32, while hydraulic fluid is discharged from the hydraulic actionchambers 31 and 33. As a result, the rotor 7 is rotated in the clockwisedirection as viewed in FIG. 3a until it reaches the state indicated inFIG. 4a.

Inversely, when the rotation of the input shaft '3 oper-' ates thecontrol valve 8 in a manner to communicate the fluid dischargepassageway 14 with the hydraulic action chambers 30 and 32 and the fluidsupply passageway 13 with the'hydraulic action chambers 31 and 32,hydraulic fluid is discharged from the chambers 30 and 32, whilehydraulic fluid is supplied into the chambers 31 and 33, whereby therotor 7 is rotated counterclockwise until it reaches the state indicatedin FIG. 5a.

A vitally important feature of this invention lies in the provision of aseparate control valve 50 for limiting the quantity of the hydraulicfluid entering the fluid chambers thereby to prevent thepressure-actuated vane members 7A and 7B of the rotor 7 from collidingwith the longitudinal partition walls 6A and 6B of the cylin dricalenclosure 1 at the time of rotation, this control valve 50 beingprovided at the slidably fitted surfaces of the input shaft 3, theoutput shaft 2, and the end wall 5 of the enclosure 1.

In the construction indicated in FIGS. 1 and 2, the right end (as viewedin FIG. 1) of the output shaft 2, being provided with a central bore 12,for rotatably accommodate the input shaft 3, has the shape of a sleeve2S rotatably fitted in the journal hole 58 of the end wall 5 asmentioned hereinbefore. The end wall 5 is provided with a hydraulicfluid supply inlet 17 and discharge outlet 18, which are respectivelyconnected by suitable piping (not shown) to the aforementioned hydraulicfluid supply source and reservoir. The inlet 17 and the outlet 18 ontheir inner sides are communicatively connected by a hydraulic fluidsupply passageway 15 and a hydraulic fluid discharge passageway 16,respectively to the journal bore 58.

The sleeve-shaped part 25 of the output shaft 2 is provided in its outerperipheral surface with arcuate fluid grooves 19 and 20 adapted tocommunicate with the fluid supply passageway 15 and discharge passageway16 at their endsopening into the bore 58 in accordance with the angularposition of the output shaft 2. The fluid grooves 19and 20 arecommunicatively connected respectively by radially extending passageways21 and 22 in the output shaft 2'to the central bore 12 of the outputshaft 2. I

The input shaft 3 is provided in its outer peripheral surface witharcuate fluid grooves 23 and 24 communicatively connected on their innersides to the aforedescribed fluid supply passageway 13 and fluiddischarge passageway 14, respectively. Furthermore, these fluid grooves23 and 24 are adapted to communicate on their outer sides with the inneropen ends of the above mentioned radial passageways 21 and 22 providedin the sleeve part 28 of the output shaft 2.

With the essential parts of the actuator in their relative positionsindicated in FIGS. 1 and 2, the fluid supply passageway 13 in the inputshaft 3 is in communication by way of the arcuate fluid groove 23, theradial passageway 21, the arcuate groove 19, and the radial supplypassageway 15 with the fluid inlet 17, while the fluid dischargepassageway 14 is in communication by way of the arcuate groove 24, theradial passageway 22, the arcuate groove 20, and the radial dischargepassageway 16 with the fluid outlet 18.

In the case where the input shaft 3 is rotated in the counterclockwisedirection, for example, from the state indicated in FIGS. 1 and 2, theoutput shaft 2 follows up this rotation and rotates counterclockwise asa result of the functioning of this hydraulic servo-actuator. Duringthis operation, since the servo-valve 8 returns automatically to theneutral position, the output shaft 2 stops at a specific angularposition. I

However, by appropriately selecting the length S of the arc of thearcuate fluid groove 19 provided in the sleeve part 2S of the outputshaft 2 as shown in FIG. 2,

the ledge or shoulder 198 of the fluid groove 19 can be caused to closethe fluid supply passageway in the end wall 5 thereby to shut off thesupply of hydraulic fluid to the supply passageway 13 within the inputshaft 3. Consequently, at a stage prior to the action of the controlvalve 8, which is an essential characteristic of 5 this actuator, thefluid supply is shut off. Therefore, the control valve 50 comprising thearcuate grooves 19 and of the output shaft 2 and the hydraulic fluidsupply and discharge passageways l5 and 16 of the end wall 5 constitutesa safety device for preventing excessive rotation of the rotor 7.

The neutral position of the control valve 50 is dia' grammaticallyindicated in FIG. 3b, while its operational position at the time whenthe output shaft 2 has rotated counterclockwise is indicated in FIG. 4b.The width of the arcuate fluid groove 19 is reduced at its end asindicated in FlG. 6.

What we claim is:

1. A hydraulic, rotary servo-actuator comprising:

a closed cylindrical enclosure having therewithin a plurality ofhydraulic action chambers;

an input shaft entering said enclosure one end.

thereof and rotatably and coaxially supported therewithin;

an actuated member comprising a part having a central axial bore, intowhich said input shaft is rotatably fitted, a rotor part provided withhydraulically actuated parts movably disposed within said chambers, andan output shaft connected unitarily to said rotor part;

a first control valve provided in said input shaft and central axialbore and operating to communicate the chambersselectively with hydraulicfluid supply and discharge passageways formed within the input shaft; I

other hydraulic fluid supply and discharge passageways formed within awall of the enclosure and respectively communicating with a hydraulicfluid supply source and a hydraulic fluid reservoir both outside of theservo-actuator; and

a second control valve provided within the input shaft and central axialbore and operating interrelatedly with said first control valve tocommunicate and shut off selectively said other supply and dischargepassageways respectively with and from the aforesaid passageways formedwithin the input shaft thereby to prevent excessive actuated movement ofsaid hydraulically actuated parts.

2. A hydraulic, rotary servo-actuator as set forth in claim 1 in whichsaid second control valve is constituted by pertinent parts of the inputshaft, the actuated member, and said wall of the enclose which definesaid other hydraulic fluid supply and discharge passageways, groovesformed in an outer surface of the actuated member to perform valveaction cooperatively with said passageways and communicating with thirdpassageways leading to the peripheral surface of the input shaft,grooves formed in said peripheral surface of the input shaft to performvalve action cooperatively with said third passageways and communicatingwith the first mentioned passageways formed in the input

1. A hydraulic, rotary servo-actuator comprising: a closed cylindricalenclosure having therewithin a plurality of hydraulic action chambers;an input shaft entering said enclosure one end thereof and rotatably andcoaxially supported therewithin; an actuated member comprising a parthaving a central axial bore, into which said input shaft is rotatablyfitted, a rotor part provided with hydraulically actuated parts movablydisposed within said chambers, and an output shaft connected unitarilyto said rotor part; a first control valve provided in said input shaftand central axial bore and operating to communicate the chambersselectively with hydraulic fluid supply and discharge passageways formedwithin the input shaft; other hydraulic fluid supply and dischargepassageways formed within a wall of the enclosure and respectivelycommunicating with a hydraulic fluid supply source and a hydraulic fluidreservoir both outside of the servo-actuator; and a second control valveprovided within the input shaft and central axial bore and operatinginterrelatedly with said first control valve to communicate and shut offselectively said other supply and discharge passageways respectivelywith and from the aforesaid passageways formed within the input shaftthereby to prevent excessive actuated movement of said hydraulicallyactuated parts.
 2. A hydraulic, rotary servo-actuator as set forth inclaim 1 in which said second control valve is constituted by pertinentparts of the input shaft, the actuated member, and said wall of theenclose which define said other hydraulic fluid supply and dischargepassageways, grooves formed in an outer surface of the actuated memberto perform valve action cooperatively with said passageways andcommunicating with third passageways leading to the peripheral surfaceof the input shaft, grooves formed in said peripheral surface of theinput shaft to perform valve action cooperatively with said thirdpassageways and communicating with the first mentioned passagewaysformed in the input shaft.